1. Field of the Invention
The present invention relates to an ice making machine, and more particularly to an ice making machine for making spherical ice cubes or ice balls suitable for use in deburring, shot blasting, hydraulic honing or similar applications.
2. Description of the Prior Art
In Japanese Patent Laid-open Publication No. 1-210773, there has been proposed an ice making machine which comprises a cooling vessel arranged to store an amount of liquid cooling medium and an amount of separation medium located above the cooling medium. Refrigeration means are provided for refrigerating both the mediums and water supply means are provided for supplying fresh water in the form of water drops into the liquid cooling medium. The water drops are formed into spherical ice cubes or ice balls as the water drops rise in the liquid cooling medium, and the formed ice balls are then separated from the liquid cooling medium in the separation medium to be harvested. In this ice making machine a fluorocarbon solution is used as the liquid cooling medium, and water is used as the separation medium.
In this ice making machine, however, the water temperature must be maintained at approximately 0.degree. C. in order to prevent the ice balls formed in the fluorocarbon solution from combining with each other into ice blocks in the separation medium, and also from dissolution in the separation medium. To solve these problems, these ice making machines can be equipped with a heater, an agitator, and a thermal control apparatus for precise control of the water temperature. With reason, these added elements however, the ice making machine becomes complicated in construction and large in size, resulting in an increase of the manufacturing cost. This type of device also fails to prevent that the separation medium or water from becoming frozen at the controlled temperature of approximately 0.degree. C. and also fails to prevent the formed ice balls from becoming melted and combined into ice blocks.